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Table 3 Statistics (mean, standard deviation, and range) of the number of projections, monitor units, and CBCT image quality metrics calculated across 16 VMAT plans compared between the CBCT images acquired with the tube currents of 20 and 40 mA

From: Image quality of 4D in-treatment CBCT acquired during lung SBRT using FFF beam: a phantom study

 

Tube current: 20 mA

Tube current: 40 mA

Mean, standard deviation (range)

Pearson correlation

Mean, standard deviation

(range)

Pearson correlation

r

p

r

p

Number of projections acquired

623 ± 225 (379–1170)

  

617 ± 237 (346–1194)

  

Monitor units

2063 ± 1221 (154–4525)

0.92

0.00

2063 ± 1221 (154–4525)

0.94

0.00

Contrast (%)

8.1 ± 0.5 (7.4–9.1)

− 0.10

0.72

8.6 ± 0.5 (8.2–10.2)

− 0.41

0.12

Contrast-to-noise ratio

5.7 ± 1.2 (3.1–8.1)

− 0.04

0.89

8.5 ± 1.5 (5.4–10.8)

0.55

0.03

Overall uniformity (%)

96.0 ± 2.5 (87.1–98.0)

0.32

0.23

96.9 ± 1.9 (92.0–97.9)

0.48

0.06

Minimum uniformity (%)

97.2 ± 0.7 (95.6–98.0)

0.31

0.24

98.2 ± 0.3 (97.3–98.7)

0.59

0.02

  1. Furthermore, the Pearson correlation coefficients r and corresponding p-value p were calculated between the number of projections acquired and each of the other variables (the monitor units and CBCT image quality metrics)